changing username

Hi, I would like to change my username to crivortscigliano, but I would like to make sure that when someone type the old username (silviaemarciaemny) it will be redirect to the new one. which one os the 4 options should I choose?
tks, Silvia.

Hi, thanks!
I am thinking in buying a domain: crivorotscigliano.com, but would like to make sure that all my current blog (silviaemarciaemny.wordpress.com), like current design, posts, comments and traffic are going to be transferred to the new address (crivorotscigliano.com) and keep the same...
Also, if someone types the current address (silviaemarciaemny.wordpress.com), will she be transferred to the new one (crivorotscigliano.com)?

If you want to change your existing __.wordpress.com address for a __.com address, the domain mapping upgrade does just that. If you follow all the steps, your old __.wordpress.com address will automatically redirect to your new __.com address.http://en.support.wordpress.com/domain-mapping/